U.S. patent application number 13/804137 was filed with the patent office on 2013-10-03 for image forming apparatus.
This patent application is currently assigned to Brother Kogyo Kagushiki Kaisha. The applicant listed for this patent is Tomoya Yamamoto. Invention is credited to Tomoya Yamamoto.
Application Number | 20130259528 13/804137 |
Document ID | / |
Family ID | 47891521 |
Filed Date | 2013-10-03 |
United States Patent
Application |
20130259528 |
Kind Code |
A1 |
Yamamoto; Tomoya |
October 3, 2013 |
Image Forming Apparatus
Abstract
An image forming apparatus including a drive source, a rotating
body, a processing unit, and a joint to switch transmission and
disconnection of the driving force by moving along an axial
direction, is provided. The joint is rotatable by the driving force
transmitted from the rotating body in a coaxial position with
respect to the rotating body and switches transmission and
disconnection of the driving force by moving along the axial
direction. The rotating body includes an input rotating body, which
is subject to the driving force input in the rotating body and
rotatable by the driving force, and an output rotating body, which
is arranged coaxially with respect to the input rotating body and
rotatable integrally with the input roller to output the driving
force. The rotating body provides accommodating space, which
accommodates at least a part of the joint when the joint is
separated from the processing unit.
Inventors: |
Yamamoto; Tomoya;
(Nagoya-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Yamamoto; Tomoya |
Nagoya-shi |
|
JP |
|
|
Assignee: |
Brother Kogyo Kagushiki
Kaisha
Nagoya-shi
JP
|
Family ID: |
47891521 |
Appl. No.: |
13/804137 |
Filed: |
March 14, 2013 |
Current U.S.
Class: |
399/167 |
Current CPC
Class: |
G03G 15/757 20130101;
G03G 21/186 20130101; G03G 21/1857 20130101; G03G 2221/1657
20130101; G03G 21/1633 20130101; G03G 21/1647 20130101 |
Class at
Publication: |
399/167 |
International
Class: |
G03G 15/00 20060101
G03G015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2012 |
JP |
2012-074613 |
Claims
1. An image forming apparatus configured to form an image on a
sheet, comprising a drive source attached to a body of the image
forming apparatus and configured to generate driving force; a
rotating body arranged on the body of the image forming apparatus
and configured to be rotated by the driving force supplied from the
drive source; a processing unit comprising an operable member and
detachably attached to the body of the image forming apparatus, the
operable member being driven by the driving force transmitted from
the rotating body; and a joint configured to switch transmission
and disconnection of the driving force from the rotating body to
the processing unit by moving along an axial direction of the
rotating body between a first position, in which the joint is
engaged with the processing unit, and a second position, in which
the joint is separated from the processing unit, wherein the joint
is rotatable by the driving force transmitted from the rotating
body in a coaxial position with respect to the rotating body and
switches transmission and disconnection of the driving force by
moving along the axial direction; wherein the rotating body
comprises an input rotating body, which is subject to the driving
force input in the rotating body and rotatable by the driving
force, and an output rotating body, which is arranged coaxially
with respect to the input rotating body and rotatable integrally
with the input roller to output the driving force; and the rotating
body provides accommodating space, which accommodates at least a
part of the joint when the joint is separated from the processing
unit.
2. The image forming apparatus according to claim 1, wherein the
input rotating body and the output rotating body are arranged on an
outer circumference of a cylindrically-formed part, of which inner
circumference defines the accommodating space; wherein the joint is
drawn into ranges corresponding to the input rotating body and the
output rotating body in the accommodating space when the joint is
separated from the processing unit.
3. The image forming apparatus according to claim 2, wherein the
input rotating body is a driven pulley, around which an endless
belt to transmit the driving force is strained.
4. The image forming apparatus according to claim 3, further
comprising: a driving pulley, configured to drive the belt, and
around which the endless belt is strained; and a reducer configured
to reduce the driving force from the drive source and transmit the
reduced driving force to the driving pulley.
5. The image forming apparatus according to claim 3, wherein a
support member to support the rotating body is arranged in a
position at one of axial ends of the rotating body; and wherein the
driven pulley is arranged in a position closer to the support
member with respect to the output rotating body.
6. The image forming apparatus according to claim 1, wherein the
input rotating body is a driven pulley, around which an endless
belt to transmit the driving force is strained.
7. The image forming apparatus according to claim 6, further
comprising: a driving pulley, configured to drive the belt, and
around which the endless belt is strained; and a reducer configured
to reduce the driving force from the drive source and transmit the
reduced driving force to the driving pulley.
8. The image forming apparatus according to claim 6, wherein a
support member to support the rotating body is arranged in a
position at one of axial ends of the rotating body; and wherein the
driven pulley is arranged in a position closer to the support
member with respect to the output rotating body.
9. The image forming apparatus according to claim 1, wherein the
accommodating space is in a cylindrical shape, of which outline is
traced along the axial direction; and wherein a circumference of
the cylindrical shape defining the accommodating space provides a
plain surface, which traces straight along a direction in parallel
with the axial direction.
10. The image forming apparatus according to claim 1, wherein the
output rotating body is a gear; and wherein the image forming
apparatus further comprises: a fixing device configured to fix a
developer agent transferred onto the sheet thereat; and a
transmission gear configured to be engaged with the output rotating
body and transmit the driving force to the fixing device.
11. The image forming apparatus according to claim 1, wherein the
output rotating body is a gear; and wherein the image forming
apparatus further comprises: a conveyer unit configured to convey
the sheet; and a transmission gear configured to be engaged with
the output rotating body and transmit the driving force to the
conveyer unit.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from Japanese Patent
Application No. 2012-074613, filed on Mar. 28, 2012, the entire
subject matter of which is incorporated herein by reference.
BACKGROUND
[0002] 1. Technical Field
[0003] An aspect of the present invention relates to an image
forming apparatus capable of forming an image on a sheet.
[0004] 2. Related Art
[0005] An image forming apparatus with a processing unit, which is
detachably attached to a body of the image forming apparatus, is
known. A driving shaft to transmit driving force to the processing
unit may retract toward the body to clear a path to the processing
unit when the processing unit is detached from the body of the
image forming apparatus.
SUMMARY
[0006] Meanwhile, there is demand for effectively size-reduced
image forming apparatuses.
[0007] The present invention is advantageous in that a
size-reducible image forming apparatus is provided.
[0008] According to an aspect of the present invention, an image
forming apparatus configured to form an image on a sheet is
provided. The image forming apparatus includes a drive source
attached to a body of the image forming apparatus and configured to
generate driving force; a rotating body arranged on the body of the
image forming apparatus and configured to be rotated by the driving
force supplied from the drive source; a processing unit comprising
an operable member and detachably attached to the body of the image
forming apparatus, the operable member being driven by the driving
force transmitted from the rotating body; and a joint configured to
switch transmission and disconnection of the driving force from the
rotating body to the processing unit by moving along an axial
direction of the rotating body between a first position, in which
the joint is engaged with the processing unit, and a second
position, in which the joint is separated from the processing unit.
The joint is rotatable by the driving force transmitted from the
rotating body in a coaxial position with respect to the rotating
body and switches transmission and disconnection of the driving
force by moving along the axial direction. The rotating body
includes an input rotating body, which is subject to the driving
force input in the rotating body and rotatable by the driving
force, and an output rotating body, which is arranged coaxially
with respect to the input rotating body and rotatable integrally
with the input roller to output the driving force. The rotating
body provides accommodating space, which accommodates at least a
part of the joint when the joint is separated from the processing
unit.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0009] FIG. 1 is an external perspective view of an image forming
apparatus 1 according to an embodiment of the present
invention.
[0010] FIG. 2 is a cross-sectional view of the image forming
apparatus 1 according to the embodiment of the present
invention.
[0011] FIG. 3 is an illustrative side view of a frame 17 on a
left-hand side with a driving pulley 23 and a driven pulley 25 in
the image forming apparatus 1 according to the embodiment of the
present invention.
[0012] FIG. 4 is a cross-sectional view of the frame 17 with the
driving pulley 23 and the driven pulley 25 in the image forming
apparatus 1 according to the embodiment of the present invention
taken along a line A-A shown in FIG. 3.
[0013] FIG. 5 is a partially enlarged view of the driven pulley 25
and surroundings in an engaged position in the image forming
apparatus 1 according to the embodiment of the present
invention.
[0014] FIG. 6 is a partially enlarged view of the driven pulley 25
and surroundings in a disengaged position in the image forming
apparatus 1 according to the embodiment of the present
invention.
[0015] FIG. 7 is an illustrative side view of the frame 17 with a
second plate 33 in the image forming apparatus 1 according to the
embodiment of the present invention.
[0016] FIG. 8 is an exploded view of a joint driving system 40 in
the image forming apparatus 1 according to the embodiment of the
present invention.
[0017] FIG. 9 is an illustrative side view of a top cover 3C being
movable between an open position and a closed position in the image
forming apparatus 1 according to the embodiment of the present
invention.
[0018] FIG. 10 illustrates a movement of the joint driving system
40 in the image forming apparatus 1 according to the embodiment of
the present invention.
[0019] FIG. 11 illustrates a movement of the joint driving system
40 in the image forming apparatus 1 according to the embodiment of
the present invention.
[0020] FIGS. 12A and 12B are partially enlarged perspective views
of a linker 47 in the image forming apparatus 1 according to the
embodiment of the present invention.
[0021] FIG. 13A illustrates the top cover 3A being in the open
position in the image forming apparatus 1 according to the
embodiment of the present invention. FIG. 13B is an enlarged view
of an encircled area shown in FIG. 13A.
[0022] FIG. 14 is a cross-sectional view of the frame 17 in the
image forming apparatus 1 according to the embodiment of the
present invention taken along a line A-A shown in FIG. 7.
DETAILED DESCRIPTION
[0023] Hereinafter, an embodiment of the present invention will be
described with reference to the accompanying drawings. It is noted
that various connections are set forth between elements in the
following description. These connections in general, and unless
specified otherwise, may be direct or indirect, and this
specification is not intended to be limiting in this respect.
[0024] 1. Overall Configuration of Image Forming Apparatus
[0025] An overall configuration of an image forming apparatus 1
according to the embodiment will be described with reference to
FIG. 1. In the following description, directions concerning the
image forming apparatus 1 will be referred to in accordance with
orientation indicated by arrows in the drawings. The image forming
apparatus 1 being a monochrome image forming apparatus includes a
chassis 3, which accommodates an image forming unit 5 inside. On a
front face of the chassis 3, a swingable sheet-feeder cover 3A is
attached. On top of the chassis 3, a swingable sheet-ejection cover
3B is attached.
[0026] When an image is formed on a sheet, the sheet-feeder cover
3A and the sheet-ejection cover 3B are pivoted frontward to
positions indicated in double-dotted chain lines in FIG. 1 to be
opened so that the sheet is set on the sheet-feeder cover 3A being
open. When an image forming operation starts, the sheet set on the
sheet-feeder cover 3A is fed in the chassis 3 to the image forming
unit 5. When the image is formed on the sheet, the sheet with the
image is ejected out of the chassis 3 and caught on the
sheet-ejection cover 3B.
[0027] The image forming unit 5 is configured to form the image on
the sheet in an electro-photographic method and includes, as shown
in FIG. 2, a photosensitive drum 7A, a charger 9, an exposure
device 11, a transfer roller 13, and a fixing device 15. The
photosensitive drum 7A carries an image formed in a developer agent
on a circumference thereof. The charger 9 electrically charges the
circumference of the photosensitive drum 7A. The exposure device 11
emits a laser beam to the circumference of the photosensitive drum
7A to form a latent image on an area exposed to the laser beam on
the circumference of the photosensitive drum 7A. The transfer
roller 13 transfers the image formed in the developer agent and
carried on the circumference of the photosensitive drum 7A onto the
sheet. The fixing device 15 fixes the image transferred on the
sheet.
[0028] The photosensitive drum 7A is contained in a casing 7B and
is rotatable. The casing 7B further contains the developer agent
and a developer device (not shown), which supplies the developer
agent to the photosensitive drum 7A. The photosensitive drum 7A,
the casing 7B, and the developer device are included in a
processing unit 7.
[0029] The processing unit 7 is detachably attached to a body of
the image forming apparatus 1. The body of the image forming
apparatus 1 includes frames 17 (see FIG. 3), the chassis 3, and
other components, which are not to be removed or detached by a user
in regular use. The frames 17 are a pair of panels, which are
arranged on lateral (right and left) sides of the image forming
unit 5 including the processing unit 7. The frames 17 may be made
of, for example, resin.
[0030] The operable components and units which are to be driven by
external force, such as the photosensitive drum 7A in the
processing unit 7 and the developer device, are driven by driving
force generated in a drive source 19 in the image forming apparatus
1. The drive source 19 is, for example, an electrical motor and
generates rotating force. The drive source 19 is attached to one of
the paired frames 17. In the present embodiment, the drive source
is attached to one of the frames 17, which is on a left-hand side.
Further, in the following description, unless otherwise noted, the
frame 17 denotes the one on the left-hand side. However, the drive
source may not necessarily be attached to the frame 17 on the
left-hand side but may be attached to the frame 17 on a right-hand
side.
[0031] The fixing device 15 includes, as shown in FIG. 2, a heat
roller 15A and a pressure roller 15B. The heat roller 15A is
rotated by the driving force form the drive source 19 and heats the
sheet being conveyed. The pressure roller 15B is driven along with
the rotation of the heat roller 15A and urges the sheet against the
heat roller 15A.
[0032] A feeder unit 21 conveys the sheet placed on the
sheet-feeder cover 3A to the image forming unit 5. The feeder unit
21 includes a pickup roller 21A, which is rotated by the driving
force supplied from the drive source 19, and a separator 21B.
[0033] The pickup roller 21A is arranged to be in contact with one
of sheets stacked on the sheet-feeder cover 3A, in particular, one
of the sheets at one end of the stack along a stacking direction,
and is rotated to move the sheet at the one end. The separator 21B
separates the one of the sheets at the one end from the stacked
other sheets and forwards the separated sheet toward the image
forming unit 5.
[0034] A conveyer roller 22A conveys the sheet passed from the
separator 21B toward the photosensitive drum 7A and the transfer
roller 13. An ejection roller 22B forwards the sheet passed from
the fixing device 15 toward the sheet-ejection cover 3B to
eject.
[0035] A pressure roller 22C urges the sheet against the conveyer
roller 22A and is rotated along with the sheet being conveyed. A
pair of pressure rollers 22D urges the sheet against the ejection
roller 22B to remove curl from the sheet and is rotated along with
the sheet being ejected.
[0036] 2. Transmission of Driving Force from the Drive Source to
the Processing Unit and the Feeder Unit
[0037] 2.1 Transmission of Driving Force to the Processing Unit
[0038] In positions opposite from the processing unit 7 across the
one of the paired frames 17, to which the drive source 19 is
attached, as shown in FIG. 3, a driving pulley 23 and a driven
pulley 25 are arranged. Rotation axes of the driving pulley 23 and
the driven pulley 25 extend in parallel with each other.
[0039] An endless belt 27 is strained around the driving pulley 23
and the driven pulley 25, and the driving force is transmitted from
the driving pulley 23 to the driven pulley 25 via the belt 27. The
belt 27 is a toothed belt with teeth, which mesh with teeth formed
on outer circumferences of the driving pulley 23 and the driven
pulley 25.
[0040] The driving force from the drive source 19 is reduced by a
reducer 29 and transmitted to the driving pulley 23. The reducer 29
is a gear system including a larger gear 29A and a smaller gear
29B. The larger gear 29A is arranged in a coaxial position with the
driving pulley 23 and rotates along with the driving pulley 23. The
smaller gear 29B is arranged to mesh with the larger gear 29A and
is rotated by the driving source supplied from the drive source
19.
[0041] As shown in FIG. 4, the driving pulley 23 and the larger
gear 29A are integrally formed in resin to configure a first
rotating body 23A. Therefore, the larger gear 29A is a rotating
body on a driving side, which rotates along with the driving pulley
23 being rotated by the driving force from the drive source 119,
while a second rotating body 25A is a rotating body on a driven
side, which is driven by the driving force input through the belt
27. The second rotating body 25A will be described below in
detail.
[0042] The driving pulley 23 is arranged on a side opposite from
the frame 17 across the larger gear 29A. A shaft 23B, which
supports the first rotating body 23A rotatably, is fixed to a
metal-made first plate 23C, while the first plate 23C is fixed to
the frame 17.
[0043] The first plate 23C is arranged on the side of the
processing unit 7 with respect to the frame 17 and is fixed to the
frame 17 by a fastening means such as a screw (not shown). The
shaft 23B is fixed to the first plate 23C by swaging and penetrates
the frame 17 to protrude from the frame 17 to reach the side of the
first rotating body 23A.
[0044] The driven pulley 25 is an input rotating body on the driven
side, which is rotated by the driving force input through the belt
27. An output gear 31 is arranged in a coaxial position with
respect to the driven pulley 25 and rotates along with the driven
pulley 25 to output the driving force. The output gear 31 in the
present embodiment is a helical gear, of which teeth are formed to
incline with respect to a rotation axis.
[0045] The driven pulley 25 and the output gear 1 are formed in
resin integrally to configure the second rotating body 25A. The
second rotating body 25A is an input rotating body subjected to the
driving force, which is input from the drive source 19 via the belt
27, and is rotatable by the driving force.
[0046] The second rotating body 25A includes, as shown in FIG. 5, a
cylindrically-formed cylinder part 25B, a hub 25C, which is formed
to close one axial end of the cylinder part 25B, and a tubular
bearing 25E, in which a shaft 25D is inserted. The second rotating
body 25A is rotatably supported in the bearing 25E by the shaft
25D.
[0047] The driven pulley 25 and the output gear 31 are formed in
resin on an outer circumference of the cylinder part 25B integrally
with the cylinder part 25B, the hub 25C, and the bearing 25E. The
cylinder part 25B is formed to be open-ended at the other axial end
opposite from the hub 25C. An inner circumference 25F of the
cylinder part 25B is formed in a plain surface traced in parallel
with an axis of the cylinder part 25B. Accordingly,
cylindrically-shaped hollow space 25G is formed inside the cylinder
part 25B.
[0048] While the second rotating body 25A is integrally formed with
the bearing 25E, it may be viewed that the second rotating body 25A
is in a shape of a tube cake. Therefore, it may be viewed that the
space 25G formed inside the cylinder part 25B is in a shape of the
tube cake.
[0049] The shaft 25D is fixed to a metal-made second plate 33 at
one axial end thereof. As shown in FIG. 7, the second plate 33 is
arranged in a position opposite from the frame 17 across the second
rotating body 25A to cover the second rotating body 25A laterally
and fixed to the frame 17.
[0050] The shaft 25D is in a cantilever structure held solely at
the one axial end on the side of the second plate 33. In other
words, the second plate 33 supports the second rotating body 25A
via the shaft 25D. Meanwhile, as shown in FIG. 5, the driven pulley
25 is arranged in a position closer to the second plate 33 with
respect to the output gear 31 in the cylinder part 25B.
[0051] The shaft 25D is fixed to the second plate 33 by swaging,
and the second plate 33 is fixed to the frame 17 by a fastening
means, such as screws (unsigned). The belt 27 is strained by a
predetermined intensity of tensile force applied by a tensile force
applier 27A (see FIG. 3), which utilizes resiliency of, for
example, a spring.
[0052] In the space 25G in the second rotating body 25A, as shown
in FIG. 5, a joint 35 is housed. The joint 35 is rotated by the
driving force input to the second rotating body 25A. The joint 35
is arranged in a coaxial position with respect to the second
rotating body 25A and is movable in the axial direction of the
second rotating body 25A. As the joint 35 moves in the axial
direction, transmission and disconnection of the driving force from
the second rotating body 25A to the processing unit 7 is switched.
In the following description, the space 25G may be referred to as
accommodating space 25G. A structure to move the joint 35 in the
axial direction will be described later in detail.
[0053] The joint 35 is a movable member including a tubular movable
part 35A and an engaging part 35B. The engaging part 35B is
engageable with an engageable part 7C in the processing unit 7,
which transmits the driving force transmitted from the joint 35 to
the operable components such as the photosensitive drum 7A.
[0054] The movable part 35A is movable in the axial direction while
being engaged with the bearing 25E. The engaging part 35B is formed
integrally with the movable part 35A on one of axial ends of the
movable part 35A. As shown in FIG. 5, when the joint 35 is in a
position closer to the processing unit 7 and the engaging part 35B
engages with the engageable part 7C, a transmission path to convey
the driving force from the second rotating body 25A, i.e., the
driven pulley 25, to the processing unit 7 is established.
[0055] As shown in FIG. 6, on the other hand, when the joint 35 is
shifted to a separated position farther from the processing unit 7
to be closer to the second plate 33, the engaging part 35 is
disengaged from the engageable part 7C; therefore, the transmission
path to convey the driving force from the second rotating body 25A,
i.e., the driven pulley 25, to the processing unit 7 is
disconnected.
[0056] When the joint 35 is separated from the processing unit 7,
the engaging part 35B is entirely withdrawn from an inner plane 17A
of the frame 17, which is a plane of the frame 17 on the side of
processing unit 7, to the side of the second rotating body 25A. In
this regard, the joint 35 is partly housed in the accommodating
space 25G into ranges coincident with the driven pulley 25 and with
the output gear 31.
[0057] In the present embodiment, the joint 35 being in the ranges
in the accommodating space 25G coincident with the driven pulley 25
and the output gear 31 denotes a condition of the joint 35, of
which other one of axial ends, i.e., an axial end opposite from the
engaging part 35B, reaches a range B corresponding to the driven
pulley 25 in the accommodating space 25G across a range A
corresponding to the output gear 31 (see FIG. 6).
[0058] 2.2 Transmission of Driving Force to the Feeder unit
[0059] The operable components stored in the processing unit 7,
such as the photosensitive drum 7A, are driven by the driving force
transmitted from the second rotating body 25A via the joint 35.
Meanwhile, sheet-conveying components not contained in the
processing unit 7, such as the feeder unit 21, the fixing device
15, and conveying rollers are, as shown in FIG. 3, rotated by the
driving force transmitted via transmission gears 37A-37C, which are
meshed with the output gear 31.
[0060] The transmission gear 37A conveys the driving force to the
rollers in the feeder unit 21, including the pickup roller 21 and
the conveyer roller 22A. The transmission gear 37B conveys the
driving force to the transfer roller 13. The transmission gear 37C
conveys the driving force to the heat roller 15A and the ejection
roller 22B. The transmission gears 37A-37C and other gears which
mesh with the transmission gears 37A-37C are rotatably supported by
the frame 17.
[0061] 3. Driving System for the Joint
[0062] 3.1 Configuration of Joint Driving System and Movements with
the Driving System
[0063] A joint driving system 40 will be described herein below.
The joint driving system 40 being a known driving system and moves
the joint 35 between an engaged position (FIG. 5), in which the
engaging part 35B is engaged with the engageable part 7C, and a
disengaged position (FIG. 6), in which the engaging part 35B is
disengaged from the engageable part 7C to be separated from the
processing unit 7.
[0064] As shown in FIG. 8, the joint driving system 40 includes the
joint 35, a rotation cam 41, a translation cam 43, a restricting
cam 45, a linker 47, and a spring 49.
[0065] The rotation cam 41 is, as shown in FIG. 9, coupled to the
top cover 3C through the linker 47. The rotation cam 41 is
rotatable about the shaft 25D with respect to the frame 17 in
conjunction with the movement of the top cover 3C.
[0066] The top cover 3C is swingably attached to the chassis 3 and
is swingable between an open position, in which an opening (not
shown) formed in the chassis 3 is exposed, and a closed position,
in which the opening is closed. The opening is formed in an upper
position of the chassis 3 and is exposed when, for example, the
processing unit 7 is exchanged. With the opening being exposed, the
processing unit 7 can be removed from and installed in the image
forming apparatus 1 through the opening.
[0067] The rotation cam 41 includes, as shown in FIG. 8, a first
slider edge 41A, which is formed to protrude in a helix curving
around a rotation axis of the rotation cam 41. The translation cam
43 includes a slider part 43B and an engageable part 43C and is
movable to shift positions thereof in an axial direction according
to a rotation angle of the rotation cam 41.
[0068] The slider part 43B is formed to have a slidable edge 43A,
which slidably contacts the first slider edge 41A of the rotation
cam 41. The engageable part 43C is engageable with a flange 35C
formed in the joint 35.
[0069] The translation cam 43 is, as shown in FIGS. 10 and 11,
movable to shift positions thereof in an axial direction L1 along
with the joint 35 with the slider part 43B sliding with respect to
the first slider edge 41A as the rotation cam 41 rotates due to a
screwing principle (a wedging effect).
[0070] The restricting cam 45 includes, as shown in FIG. 10, a
second slider edge 45A, which slidably contacts an edge of the
slider part 43B in the translation cam 43 at a side opposite from
the first slider edge 41A across the slider part 43B. It is to be
noted that each of the first slider edge 41A, the second slider
edge 45A, and the slidable edge 43A includes two pieces, which are
arranged in rotationally symmetric positions with respect to the
rotation axis of the rotation cam 41.
[0071] As shown in FIGS. 10 and 11, the second slider edge 45A of
the restricting cam 45 is formed to incline in a reversed angle
with respect to the helical inclination of the first slider edge
41A. Therefore, as the rotation cam 41 rotates, the translation cam
43 shifts positions thereof in the axial direction L1 along with
the rotation of the rotation cam 41 and therefore moves the joint
35 in the axial direction L1.
[0072] For example, when the rotation cam 41 rotates to bring a
corner point P1 of the first slider edge 41A and the corner point
P2 of the second slider edge 45A relatively closer to each other,
as shown in FIG. 11, the slidable edge 43A and the first slider
edge 41A contact each other, and the slider part 43B of the
translation cam 43 is urged against the second slider edge 45A.
[0073] In this regard, while the restricting cam 45 including the
second slider edge 45A is not movable, compression force F3 to move
the slider part 43B in a direction to compress the spring 49 is
generated in a contact surface between the slider part 43B and the
first slider edge 41A and in a contact surface between the slider
part 43B and the second slider edge 45A.
[0074] Thus, the translation cam 43 moves in the direction of the
compression force F3, and the joint 35 is moved from the engaged
position to the disengaged position. In this regard, while force F1
rotates the rotation cam 41, and force F2 is a component in the
force F1 in an orientation orthogonal to the first slider edge 41A
and the slidable edge 43A, the compression force F3 is a component
in the force F2 in an orientation in parallel with the axial
direction L1.
[0075] On the other hand, when the rotation cam 41 rotates in a
direction to separate the corner point P1 of the first slider edge
41A and the corner point P2 of the second slider edge 45A apart
from each other, as shown in FIG. 10, the force F1 dissolves, and
the compression force F3 dissolves. Accordingly, the spring 49
restores to the expanded condition. Thus, the translation cam 43 is
pressed by the spring 49 to move in a direction opposite from the
compression force F3, and the joint 35 is shifted from the
disengaged position to the engaged position.
[0076] Meanwhile, as shown in FIG. 9, the linker 47 is attached to
the rotation cam 41 at one end thereof rotatably and to the top
cover 3C at the other end thereof rotatably. With the linker 47,
the opening and closing motions of the top cover 3C is converted
into the rotation of the rotation cam 41. Therefore, the joint 35
is moved in the axial direction L1 in conjunction with the swing
motions of the top cover 3C.
[0077] In the present embodiment, when the top cover 3C is in the
open position, as indicated in double-dotted chain lines shown in
FIG. 9, the joint 35 is placed in the disengaged position. When the
top cover 3C is in the closed position, as indicated in solid lines
FIG. 9, the joint 35 is placed in the engaged position.
[0078] Further, on the one end of the linker 47, as shown in FIG.
8, a pin-like boss 47A is formed. Meanwhile, the rotation cam 41 is
formed to have an arm 41B, which extends radially outwardly beyond
the restricting cam 45. The arm 41B is formed to have a connection
hole 41 C at a tip end thereof, and with the boss 47A rotatably
inserted in the connection hole 41C, the linker 47 and the rotation
cam 41 are rotatably coupled to each other.
[0079] 3.2 Linker and the Joint driving system
[0080] As shown in FIG. 3, the linker 47 partly coincides with the
belt 27 along a direction in parallel with the rotation axis of the
driving pulley 23. Therefore, when the linker 47 and the belt 27
are viewed along the direction in parallel with the rotation axis
of the driving pulley 23, the linker 47 extends in a direction to
intersect a strained part 27B of the belt 27. The strained part 27B
denotes a part of the belt 27, which extends linearly along a
direction of a tangent line between the driving pulley 23 and the
driven pulley 25.
[0081] As shown in FIGS. 12A-12B, the linker 47 has a first part
47B, which coincides with the belt 27 along the direction in
parallel with the rotation axis of the driving pulley 23, and a
second part 47C, which is displaced from the first part 47B with
respect to the direction in parallel with the rotation axis of the
driving pulley 23. The first part 47B and the second part 47C of
the linker 47 may be formed integrally in, for example, resin.
[0082] At least the first part 47B of the linker 47 is arranged in
a position between the frame 17 and the belt 27. In the present
embodiment, the second part 47C is arranged in a position displaced
from the first part toward a side opposite from the frame, i.e.,
closer to the belt 27 with respect to the first part 47B.
[0083] The second part 47C of the linker 47 is in the displaced
position to be closer to the belt 57 with respect to the first part
47B at least in a reason that the second part 47C should avoid
interference with the transmission gear 37D, which transmits the
driving force to the ejection roller 22. Therefore, if the linker
47 is not interfered with by the transmission gear 37 or any other
components when in motion, the second part 47C may not necessarily
be arranged in the displaced position with respect to the first
part 47B, but the linker 47 may be entirely arranged in a position
closer to the frame 17 than the belt 27.
[0084] The frame 17 is formed to have a stopper 17B, which holds
the linker 47, when the top cover 3C is opened, to maintain the
opened posture of the top cover 3C. The stopper 17B is resiliently
deformable to be engaged with a hook protrusion 47D formed in the
linker 47. When the hook protrusion 47D is disengaged from the
stopper 17B, the stopper 17B may be resiliently deformed to be
moved apart from the hook protrusion 47D.
[0085] The second plate 33 is formed to have a bulge 33A (FIG. 14),
which protrudes toward the belt 27, on the side of the belt 27. The
bulge 33A is formed to be closer to the belt 27 compared to the
other area of the second plate 33 which does not have the bulge
33A. The bulge 33A serves to prevent the belt 27 from being
displaced toward the second plate 33 or being deviated from the
driving pulley 23 or the driven pulley 25.
[0086] In the present embodiment, as shown in FIG. 7, the bulge 33A
is formed in a position in one of the paired strained parts 27B
closer to the tensile force applier 27A. However, the bulge 33A may
be formed on both of the paired strained parts 27 or on an entire
range covering the strained parts 27B.
[0087] In the present embodiment, the linker 47 is arranged in the
position closer to the frame 17 with respect to the belt 27.
Therefore, along a direction from the driving pulley 23 toward the
driven pulley 25, the linker 47 and the larger gear 29A being the
rotating body on the driving side are in mutually coincident
positions, and the linker 47 and the output gear 31 are in mutually
coincident positions.
[0088] 4. Features of the Image Forming Apparatus
[0089] According to the present embodiment, the accommodating space
25G to accommodate at least a part of the joint 35, when the joint
35 is separated from the processing unit 7, is formed in the second
rotating body 25A. Thus, the joint 35 is at least partially
accommodated in the area, which is occupied by the second rotating
body 25A. Therefore, it is not necessary to reserve extra space for
the joint 35 to be accommodated. In other words, the image forming
apparatus 1 may be downsized.
[0090] According to the present embodiment, the driven pulley 25
being the input rotating body and the output gear 31 being the
output rotating body are arranged on the outer periphery of the
cylinder part 25B. In the meantime, the accommodating space 25G is
formed inside the cylinder part 25B and provides accommodation to
the at least part of the joint 35, when the joint 35 is separated
from the processing unit 7, so that the joint 35 is drawn in the
ranges corresponding to the driven pulley 25 and the output gear
31.
[0091] Therefore, a large part of the space occupied by the second
rotating body 25A can be utilized to accommodate the at least a
part of the joint 35, and the image forming apparatus 1 can be
downsized even more effectively. In the above embodiment, it is to
be noted that the tubular cylinder part 25B may be formed to have a
smooth inner circumferential surface without any recognizable
protrusion or dent or may be formed to have protrusion and/or dent
on the inner circumferential surface.
[0092] According to the present embodiment, the reducer 29 to
reduce the driving force from the drive source 19 and transmit the
reduced driving force to the driving pulley 23 is provided. With
the reducer 29, a moving velocity of the belt 27 can be reduced;
therefore, it can be prevented that the belt 27 is abraded or
damaged by a faster moving velocity in a shorter time period.
[0093] When the driving force is transmitted by the belt 27, it may
be necessary that predetermined intensity of straining force to
strain the belt 27 is maintained. Therefore, the driven pulley 25
may be subject to a large amount of load due to the straining
force. However, according to the present embodiment, the second
plate 33 to support the second rotating body 25A at the one axial
end of the second rotating body 25A. Further, the driven pulley 25
is arranged in the position closer to the second plate 33 with
respect to the output gear 31.
[0094] Therefore, with the driven pulley 25 arranged in the
position closer to the second plate 33, a defect which may be
caused by the driven pulley 25 affected by the straining force,
such as being tilted, may be avoided.
[0095] According to the present embodiment, the accommodating space
25G is in a tubular shape formed along the axial direction of the
driven pulley 25, and the inner circumference 25F defining the
accommodating space 25G provides a plain surface, which traces
straight along the direction in parallel with the axial
direction.
[0096] In other words, there is no specific obstacle, which
interferes with the joint 35 when the joint 35 shifts positions
thereof. Therefore, the joint 35 can smoothly move in the
accommodating space 25G.
[0097] Further, if the driven pulley 25 and the output gear 31 are
formed integrally in injection molding, and if the inner
circumference defining the accommodating space 25 provides the
plain cylindrical surface, of which outline is traced straight
along the axial direction, the molds can be easily removed when the
driven pulley 25 and the output gear 31 are unmolded. Thus,
productivity of the second rotating body 25A can be improved.
[0098] When the driven pulley 25 and the output gear 31 are
integrally formed in injection molding, it may be necessary that
the inner circumference 25F is inclined at a predetermined angle as
a draft angle. Therefore, the plain cylindrical surface of the
inner circumference 25F traced straight along the axial direction
should include inclination of the draft angle.
[0099] According to the present embodiment, the linker 47 and a
part of the belt 27 are in coincident positions along the direction
in parallel with the rotation axis of the driving pulley 23.
[0100] If the linker 47 and the belt 27 are not in coincident
positions along the direction of the rotation axis, the linker 47
should be arranged in an area separated from the area occupied by
the belt 47. In other words, it is necessary to reserve a separated
area to be occupied the linker 47. Accordingly, a size of the image
forming apparatus 1 may be increased.
[0101] On the contrary, according to the present embodiment, the
linker 47 and the belt 27 are in partially coincident positions
along the direction in parallel with the rotation axis. Therefore,
the area in which the belt 27 is arranged is effectively used, and
the image forming apparatus can be downsized.
[0102] More Examples
[0103] Although an example of carrying out the invention has been
described, those skilled in the art will appreciate that there are
numerous variations and permutations of the image forming apparatus
that fall within the spirit and scope of the invention as set forth
in the appended claims. It is to be understood that the subject
matter defined in the appended claims is not necessarily limited to
the specific features or act described above. Rather, the specific
features and acts described above are disclosed as example forms of
implementing the claims.
[0104] For example, the joint 35 may not necessarily be
accommodated in the accommodating space 25G in the ranges
corresponding to the driven pulley 25 and the output gear 31 but
may be accommodated in one of the ranges corresponding to the
driven pulley 25 and the output gear 31.
[0105] For another example, the joint 35 may not necessarily be
drawn into the accommodating space 25G to reach the range
corresponding to the driven pulley 25 across the range
corresponding to the output gear 31. For example, when the driven
pulley 25 is in a position closer to the frame 17 with respect to
the output unit 31, the joint 35 may be drawn into the range
corresponding to the output gear 31 across the area corresponding
to the driven pulley 25.
[0106] For another example, the driving force from the drive source
19 may not necessarily be reduced to be transmitted to the driving
pulley 23 but may be directly transmitted to the driven pulley 23
without being reduced.
[0107] For another example, in the above embodiment, the shaft 25D
to support the second rotating body 25A is supported at one of the
axial ends by the second plate 33 while the driven pulley 25 is
arranged on the axial end side being supported by the second plate
33. However, the shaft 25D may be supported at the both axial ends.
For another example, the shaft 25D may be supported by the output
gear 31.
[0108] For another example, the inner circumference 25F defining
the accommodating space 25G may not necessarily provide a plain
surface, which traces straight along the axial direction in
parallel with the axial direction. For example, the inner
circumference 25F may be in a tapered shape or a stepped shape, in
which an inner diameter of the second rotating body 25A is greater
at a part closer to the output gear 31 and an inner diameter of the
second rotating body 25A is smaller at a part closer to the driven
pulley 25.
[0109] For another example, the driving force may not necessarily
be transmitted from the output gear 31 to the fixing device 15 or
to the feeder unit 21.
[0110] For another example, the linker 47 and the belt 27 may not
necessarily be in coincident positions along the direction in
parallel with the rotation axis of the driving pulley 23.
[0111] For another example, the first part 47B and the second part
47C of the linker 47 may not necessarily be bent at the mutually
coupled position, but the linker 47 may be formed linearly, or the
linker 47 may be bent at a different position from the mutually
coupled position between the first part 47B and the second part
47C.
[0112] For another example, the image forming apparatus 1 may not
necessarily be the image forming apparatus of the monochrome
electro-photographic type but may be, for example, an image forming
apparatus of direct tandem type.
* * * * *